Cordless Drill

[chippyk]

chippyk here
i have a 9.6 de walt drill with a knakered battery, i have soldered two wires red & black on the points in the drill, i was wondering can i hook up to a 12 volt battery, and how do i go about it, without melting the wires.

hope some one can help.

[jatt]

Had an old Ozito 12 volt battery drill that had the same issue, as in knackered batteries. Figured out + from - on the batt, dismantled the drill and ran (flying leads) out of the positive and negative terminal connections inside.

In your case (differences in voltage) the drill will still run obviously, but I wouldnt think it would last too long. As the rating suggests, the batt is around 12 volts. This situation is worse if its a car batt in a running car as u are looking at around 13.8V.

Obviously u need to decrease the voltage from your battery if u want to last for any period of time.

I would look at using some diodes in series as the simplest solution. These components have a positive (anode) and negative (cathode). Start from the pos connection in the drill. Hook diodes up Pos to neg in a diasy chain fashion. Therefore the neg terminal on the last diode would connect to your positive flying lead. The folks at Jaycar would stock some large diodes that could handle around 6 amp capacity to suit your needs.

This website is as good as any to explain diode basics.

www.facstaff.bucknell.edu/mastascu/eLessonsHtml/Diodes/Diode1.html#Diode

To suggest anything else would take me pages of boring theory and pictures to explain.

Usually there is a prominant band printed on diode. This should correspond to the cathode (neg side)

In a nutshell each diode will drop the voltage by around 0.6 of a volt. That gives u 3 diodes to reduce to 10.2 volts, close enuf in my opinion when hooked up to a 12 volt batt that isnt on charge.

Not sure what the current draw is on your drill, so have allowed a decent safety margin. Would also consider an in line fuse.

Good luck, hopefully I havent confused u too much.

[Kyle]

Chippyk,

I did the same thing with a 9.6 volt Makita. I pulled the battery pack apart disconnected the cells and soildered the wires to the contacts on the inside of the battery. This way the drill remains unmodified and is also weighted properly. 3 metres of twin core cable and some aligator clips and it works a treat of the car battery.

After 3 years the drill is still going strong, although it does get sporadic use.
If it dies from a voltage overload! who cares, it would have gone in the bin anyway.

[chippyk]

thanks kyle
i pulled the drill apart and soldered the wires inside, but i will give your way a try as i have a few drills i can play around with, thanking you again.

chippyk